Distribution and relation of two arm function tests, Box and Blocks test and Nine Hole Peg test, across disease severity levels and types of multiple sclerosis

Abstract

Background: Regular upper limb evaluation in persons with multiple sclerosis to detect early alterations and to monitor possible deterioration, both in gross and fine motor dexterity, is important for optimal levels of participation in life activities across the life span. The purpose of the present study was to inquire upon alterations in bilateral gross and fine manual dexterity, measured with the Box and Block test (BBT) and the Nine Hole Peg test (NHPT), in persons with MS (PwMS) across a wide range of disability levels and across MS types.

Methods: This is a secondary cross-sectional analysis of BBT and NHPT administered to 215 PwMS at all disability levels and three MS phenotypes, relapsing-remitting, primary progressive and secondary progressive (RRMS, PPMS, SPMS). To inquire on the prevalence of alterations in upper limb gross and fine dexterity, PwMS test scores were compared to normative healthy subjects' values, Abnormal values were defined as scores equal or exceeding 2 standard deviations from the normative values for NHPT and the BBT. The data of both arms was analyzed by disability level and by the type of MS. For characterization and comparisons based on disability level, the sample was divided in four groups according to the EDSS score: 0-3.5 were categorized as Mild (EDSS-Mi), EDSS>3.5 to 5.5 were categorized as Moderate (EDSS-Mo), EDSS>5.5 to 6.5 were categorized as Severe (EDSS-Se), and disability levels of 7 and beyond were categorized as Severe-non-ambulant (EDSS-SeN). Finally, correlations between UL dexterity measures bilaterally were carried out.

Results: Mean (SD) age of the sample was 54.07 (±12.81) years, with a mean (SD) disease duration of 18.91 (±10.95) years and a median EDSS (IQR) of 6.5 (5.5/7). Fifty-three% had RRMS, 19% PPMS and 28% SPMS. Almost the whole sample (96.2%) showed abnormal scores on the BBT; 91.5% had abnormal bilateral scores. Abnormal scores were present on the NHPT in 85.4% of the whole sample, with 68.9% having bilateral abnormal scores. With increase in disability levels the mean number of blocks moved was reduced and time taken to finish the NHPT was increased. The BBT and the NHPT in each arm were highly correlated over all disability levels, with correlation ranging from 0.74 to 0.86. Overall, right and left arm had statistical differences in median scores on the NHPT peg/sec (p = 0.004) but similar scores on the BBT (p = 0.57). Abnormal bilateral scores were recorded in 85% of PwRR, in 96% of PwSP and 100% of PwPP for the BBT and in about 56% of PwRR, increasing up to 80 and 85% in PwPP and PwSP for the NHPT. Progressive forms of MS presented statistically different values on the BBT (p<0.001) and the NHPT (p<0.001) with respect to the RRMS type.

Conclusion: We found that both fine and gross manual dexterity were altered with respect to normative values in most persons with MS, but abnormalities in gross manual dexterity were more prevalent and pronounced earlier in the disease course. Similarly, with regard to MS types, bilateral alterations in gross manual dexterity were more prevalent than were fine manual dexterity in all three phenotypes considered.

Keywords: Arm function; Multiple sclerosis; Outcome measures; Rehabilitation; Upper limb.